Basic Definitions for Psychological Egoism, Hedonism and Altruism

The aim of my work is to investigate the essence of both psychological egoism and hedonism, and to reach the objections raised up by Feinberg. Acting this way, I have several purposes. First, I will give a basic definition of psychological egoism, altruism and hedonism. Then, I will present my personal vision as for the notion of psychological egoism, giving in details my three-level method. Finally, I will discuss the objections Feinberg has as for this point. My purpose is to manage to do all enumerated above and still meet the space limitations suggested for this writing.
So, I started my research for this paper. I tried to give a fairly straight forward definition of altruism, psychological egoism and hedonism. Then I realized that that was not so easy I thought before. Certainly, there turned to be too much depth in these concepts to be adequately covered in a paper of this format. Thus, I decided to provide only basics, short and clear definitions based on a synthetic analysis of the readings reviewed.
Psychological Egoism
Psychological Egoism presupposes that the only ultimate objectives one may cherish are self-directed ones. This means that, your original motivation will always be your own self-interests no matter what you do. What shapes these self-interests can gain is a matter of discussion.
Hedonism
Hedonism can be regarded as a kind of egoism. Basically, hedonism believes that pleasure or avoidance of pain is the only matter really valuable, and thus the only fair motivating factor for human –beings is gaining pleasure or avoiding pain, by all possible means. It should be also noted that the pleasures spoken here about are not just physical, in other words, material pleasures, they can be also internal, or psychological delights.

Altruism
The altruism theory upholds that people sometimes take care about the wellbeing of others without any benefit for themselves. But at the same time altruism no way say that one will always have just well-being of the other people in mind and it does not say that it is normal for a person to have the wellbeing of others as a principle motive. This is an indirect opposition to psychological egoism stating that a person's original motivation is always merely self-directed one.
As I told before, all stated above can be regarded as the most basic of definition and this is the most acceptable within the framework of this kind of paper.